Apparatus for grinding a knife including knife holding and guiding means

ABSTRACT

A holding and guiding device for the grinding of a knife which comprises a receiving plate equipped with a form plate having a thickness approximating that of a knife. The form plate has a configuration corresponding to the profile of a groove in the knife.

[ Oct. 7, 1975 United States Patent [191 Knecht References Cited UNITED STATES PATENTS APPARATUS FOR GRINDING A KNIFE INCLUDING KNIFE HOLDING AND GUIDING MEANS [75] Inventor: Fritz Knecht, Vogt, l-Ieissen,

Germany [73] Assignee: Tecmed A.G., St. Margrethen,

1961 51/116 1970 Germany 51/3 Switzerland [22] Filed: Dec. 6, 1972 [21] Appl. No.: 312,724 Primary Examiner-Al Lawrence Smith Assistant Examiner-Nicholas P. Godici Related US. Application Data [62] Division of Ser. No. 180,306, Sept. 14, 1971 Pat.

[57] ABSTRACT A holding and guiding device for the [30] Foreign Application Priority Data Aug. 13, 1971 Germany............................ 2140596 grinding of a knife which comprises a receiving plate equipped with a form plate having a thickness approximating that of [52] US. 51/124 R; 51/128; 51/234 [51] Int. B2413 3/54 [58] Field of Search.. 51/124 R, 128, 218 R, 218 A,

a knife. The form plate has a configuration corresponding to the profile of a groove in the knife.

51/218 P, 234, 102, 96, 116; 76/892 2 Claims 6 Drawing Figures atent Oct. 7,1975

Sheet 1 of 2 US. Patent Oct. 7,1975 Sheet 2 on 3,909,985

. APPARATUS FOR GRINDING A KNIFE INCLUDING KNIFE HOLDING AND GUIDING MEANS CROSS-REFERENCE TO RELATED APPLICATION This application is a division of the copending patent application Ser. No. 180,306, filed Sept. 14, 1971, now US. Pat. No. 3,808,746.

FIELD OF THE INVENTION The present invention relates to a holding and guiding device for an apparatus for the grinding of knives, in particular of hand and cutter knives, whereby the cutting edge is pressed onto the side faces of rotating grinding discs.

BACKGROUND OF THE INVENTION During the grinding of knives used for example by butchers, in addition to a good cutting effect, it is desired to obtain long service life for the cutting edge so that work is interrupted as little as possible. Furthermore the grinding is supposed to be performed as quickly as possible and by less than skilled labor.

These requirements can be obtained only insufficiently with conventional devices, since they are prone to faulty guidance in case of manual operation. Machines have been proposed in which the knife is rigidly clamped in a predetermined position relative to the abrasive disk. These systems have the drawback that handling is complicated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a holding and guiding-device for the knife to be ground, which automatically controls suitable knife movements during operation. With these arrangement non-skilled labor can perform the grinding process quickly and exactly.

BRIEF DESCRIPTION OF THE DRAWING This and other objects will become more readily apparent from the following description, reference being made to the accompanying drawing, in which:

FIG. 1 is a top-plan view of an apparatus designed in accordance with the present invention;

FIG. 2 is an elevational view of the apparatus shown in FIG. 1;

FIG. 3 is a top-plan view of an arrangement of the grinding and holding discs;

FIG. 4 is an elevational view of the holding and guide device;

FIG. 5 is a top-plan view of a device shown in FIG. 4; and

FIG. 6 is an end view of the device shown in FIG. 5 seen in the direction of the arrow P thereof.

SPECIFIC DESCRIPTION The apparatusof FIGS. 1-3 comprises a central housing 1 for a motor having a cross drive which may include a reduction gear, the drive including oppositely disposed shafts 2 and 3. The grinding discs 6 and 7, respectively, are mounted on holding discs 4 and 5, respectively, and lapping discs 9 and 10 are respectively mounted on holding discs 8, which discs are secured to the shafts 2 and 3.

The discs 4 to 10 are provided in protective housings 11 and 12, which are laterally mounted on the motor housing 1. These protective housings 11 and 12 are equipped with oblique insert slots 13 and 14, which result, by example, in a lapping angle of 18. The term oblique beingused to indicate that'a knife blade in the slot is inclined to the axis of the shaft. Furthermore a cover tube 15 slides over each of the protective housings 1 1 and 12, which cover tube 15 has a recess 16 or l7,'respectively, for the slot 113 and 14, respectively, and which has, in addition, a longitudinal slot A, so that it is axially displaceable and rotatable/This movability can be blocked and braked by a clamping screw 18.

At its outer end each of the cover tubes 15' is equipped with a cover 19 of synthetic material extending towards the inside. This cover 19 has two insert slots 20 and 21, which are disposed on its periphe ry and are a'ngularly offset by These slots 20 and 21 have different oblique" angles, by example, the slot 20 an angle of 15 and the slot 21 an angle of only 5.

These arrangements make it possible, to perform grindings with a different grinding angle on each side. For this purpose, the knife is inserted into the slot 20 and moved slightly back and forth. In order to grind the other cutting edge chamfer, the knife is inserted into the slot 20 at the right of the motor housing 1, and one proceeds in the same manner. The lapping takes place by insertion of the knife into a slot 13 or 14, respectively.

In order to obtain hollow-ground cutting edges and a. short parallel piece before the cutting edge, the grinding line can be inclined at 5 to the radial plane of the grinding stone. If the grinding line is eccentrically displaced upwardly or downwardly, a curvature results forcibly in the grinding range (conical section), whereby a concave cutting edge is obtained, the service life of which is many times longer, than with a plane cutting edge.

The cooling takes place in a simple manner such that a container 22 is provided for the cooling medium, in which the rotating discs are suspended- Thereby the liquid'is drawn upwardly and cools the disc. A displacement of the axis of the shafts relative to the axis of the protective housing increases this effect. The arrangement of spiral-shaped grooves on the inner face of the cover 19 of synthetic material can serve the same purpose. Furthermore it is desirable, to equip the supporting edges of the slots 13 and 14 with a layer of synthetic material, so that the cutting edge of the knife is not subjected to metal-'to-metal contact. FIGS. 4' to 6 show the holding and guiding device.

A holding member or bracket 26 is secured on the cover tube 15, which can be clamped, by example, by a clamping device 18, 25. Holding member or bracket 26 receives a pivot shaft 27. A guide arm 28 is provided on the outer end of the pivot shaft 27 by means of a settable connecting member 24. The guide arm 28 extends parallel to the oblique blade-insertion plane of the guide slot 20 upwardly and. is equipped in the region of its upper end with a connecting arm 29, which is adjustably secured with respect to its position on the guide arm 28 by means of a clamping connection 30. The connecting arm 29 has a handle 31 at its outer end for the left hand.

A knife holder 32 which is of adjustable length and tightenable on the connecting arm 29 carries a receiving head 33, which is equipped with a rotary stud 34 and a receiving plate 36 for a cutter knife 37 is conneced with a hub 35 of the stud 34, for example, by means of a connecting bolt.

The blade 37 is retained by a clamp clip 38, which is secured to the receiving plate 36 by a screw. In order to secure cutter blade 37 in the correct position, the blade-sided face of the receiving plate 36 is equipped with a form plate 39 having the thickness of the knife 37 and a configuration which corresponds to the profile of the recess 40 in the blade 37.

A grip 41 is provided on the hub 35, which is operated with .the right hand of the operator and by which the hub 35 with the receiving plate 36 can swing about the axis of stud 34. The grinding disc 6 with its holding disc 4, as well as the shaft 2 and the motor housing 1 indicated partly in broken lines.

In the operation of the described device, at first the unit consisting of the parts 28 to 41, which is swingable 7 about the axis of pivot shaft 27, is turned upwardly in the direction of the arrow A (FIG. 6) by use of the grip 31 so that the cutter knife blade 37 to be grounnd can be secured to the receiving plate 36. By proper selection of a receiving plate 36 with the complementary form plate or projector (formation) 39 the axis of the stud 34 of the receiving head 33 always forms the center point of the knife chamfer with the radius R, the members 24, 30 and 32 being suitably adjusted.

By swinging of the unit in the direction of the arrow E (FIG. 6), the cutter knife 37 is inserted into the slot of the cover tube 15, into engagement with the grinding disc 6. This state is clearly indicated in FIGS. 4, 5, and 6. During the grinding process, the receiving plate 36 can be moved back and forth together with the knife 37 for the grinding process by means of the grip 41. It is then possible by use of the grip 31 to vary the engagement pressure as required, whereby by a simple lifting of the unit in the direction of the arrow A, the ground edge can be examined at any time.

Since the blade has normally a cutting chamfer on one side only, the holding device of the present invention suffices on one side only of the grinding apparatus. It is also possible, however, to simply remove the device from the holder 26, if required, and to secure the same on the grinding apparatus on the other side of the motor housing 1 in a corresponding holder.

As stated above, the holding and guiding device is characterized by extensive setting possibilities, so that blades of all existing sizes can be ground by simple exchange of the receiving plate 36 and setting of the radius R. In order to adjust thereby the position of the gripping lever 41, the hub 35 is made adjustable relative to the device joining the receiving plate, for example a bolt, by rotation and reversing of the bolt.

I claim:

1. An apparatus for grinding a knife blade comprismg:

a motor housing having a pair of driven shafts extending in opposite directions from opposite sides of said housing;

respective grinding disks mounted on each of said shafts and rotatable therewith, said disks having lateral grinding faces turned in opposite directions away from said motor housing;

a pair of protective housings fixed to said motor housings against rotation relative thereto, each of said protective housings being formed with at least one respective slot lying in a plane inclined to the axis of the respective shaft and adapted to receive a blade to be ground and to guide the blade against a respective one of said lateral faces with a predetermined grinding angle; and

a holding and guiding device for said blade for displacing same with a predetermined grinding movement automatically in said slot, said device including:

a pivot shaft mounted on one of said protective housings and defining a first pivot axis,

a guide arm swingable about said firist pivot axis,

means for adjustably securing said guide arm at a fixed orientation to said pivot shaft parallel to the one of said slots of said one of said protective housings whereby said arm is constrained to swing parallel to the last-mentioned plane,

a connecting arm extending at a right angle to said guide arm and mounted thereon for movement along said guide arm,

a first grip on said connecting arm for shifting same along said guide arm with one hand of an operator for varying pressure of the blade against a respective one of said disks, and

a blade-mounting head carrying said blade and shiftable along said connecting arm while being provided with means for fixing said head to said connecting arm.

2. The apparatus defined in claim 1 wherein said blade-mounting head includes:

a stud defining a second pivot axis perpendicular to said connecting arm and provided with a hub rotatable about said second pivot axis;

a second grip on said hub engageable by the other hand of the operator to rotate said hub about said second pivot axis;

a mounting plate fixed to said hub and swingable therewith by said second'grip, said mounting plate lying in a plane perpendicular to said second pivot axis and being provided with a formation receivable in a complementary recess formed in said blade; and

means for anchoring said blade to said plate with said recess receiving said formation and a curved cutting edge of said blade having a center of curvature coinciding with said second pivot axis. 

1. An apparatus for grinding a knife blade comprising: a motor housing having a pair of driven shafts extending in opposite directions from opposite sides of said housing; respective grinding disks mounted on each of said shafts and rotatable therewith, said disks having lateral grinding faces turned in opposite directions away from said motor housing; a pair of protective housings fixed to said motor housings against rotation relative thereto, each of said protective housings being formed with at least one respective slot lying in a plane inclined to the axis of the respective shaft and adapted to receive a blade to be ground and to guide the blade against a respective one of said lateral faces with a predetermined grinding angle; and a holding and guiding device for said blade for displacing same with a predetermined grinding movement automatically in said slot, said device including: a pivot shaft mounted on one of said protective housings and defining a first pivot axis, a guide arm swingable about said firist pivot axis, means for adjustably securing said guide arm at a fixed orientation to said pivot shaft parallel to the one of said slots of said one of said protective housings whereby said arm is constrained to swing parallel to the last-mentioned plane, a connecting arm extending at a right angle to said guide arm and mounted thereon for movement along said guide arm, a first grip on said connecting arm for shifting same along said guide arm with one hand of an operator for varying pressure of the blade against a respective one of said disks, and a blade-mounting head carrying said blade and shiftable along said connecting arm while being provided with means for fixing said head to said connecting arm.
 2. The apparatus defined in claim 1 wherein said blade-mounting head includes: a stud defining a second pivot axis perpendicular to said connecting arm and provided with a hub rotatable about said second pivot axis; a second grip on said hub engageAble by the other hand of the operator to rotate said hub about said second pivot axis; a mounting plate fixed to said hub and swingable therewith by said second grip, said mounting plate lying in a plane perpendicular to said second pivot axis and being provided with a formation receivable in a complementary recess formed in said blade; and means for anchoring said blade to said plate with said recess receiving said formation and a curved cutting edge of said blade having a center of curvature coinciding with said second pivot axis. 